#829 Renoprotective effects of laxative linaclotide: inhibition of acute kidney injury and fibrosis in a rat model of renal ischemia-reperfusion

Abstract Background and Aims Acute kidney injury caused by renal ischemia/reperfusion (I/R) is a major clinical problem in many aspects of urology fields such as kidney transplantation and partial nephrectomy, but there is no effective treatment. Linaclotide, a guanylate cyclase C agonist clinically approved as a laxative, has recently been shown to be renoprotective in a chronic kidney disease (CKD) model. Therefore, the present study investigated the possibility that the renoprotective effects of linaclotide in renal I/R may extend beyond its gastrointestinal effects. Method The left renal pelvis of adult male Wistar rats was clamped for 45 minutes to induce renal I/R injury. Kidney tissue, colon, and blood were collected 24 hours and 14 days later. Linaclotide was administered for 14 days preoperatively and until postoperative tissue collection. Tissue sections were stained with standard histologic techniques such as HE, Sirius Red, F4/80, etc. As genes associated with I/R, TGF-β and related fibrosis markers α-SMA, MMP2, TIMP1 and inflammatory cytokines TNF, IL-1β and IL-6 were analyzed by quantitative PCR analysis. Results Serum creatinine levels decreased significantly after linaclotide administration, indicating improved renal function. Histologic examination showed less tubular damage and less collagen deposition on Sirius Red staining. Further analysis showed decreased expression of TGF-β and related fibrosis markers α-SMA, MMP2 and TIMP1, suggesting downregulation of the fibrotic TGF-β pathway by linaclotide. Furthermore, 1 day after I/R injury, linaclotide significantly reduced macrophage infiltration and suppressed key proinflammatory cytokines such as TNF, IL-1β, and IL-6. Conclusion These results suggest that linaclotide, with its established safety profile, could extend its benefits beyond gastrointestinal issues and potentially serve as a therapeutic intervention in many aspects of kidney surgeries. In addition, it could provide immediate and practical insights into the selection of laxatives for the management of patients with AKI or CKD, regardless of cause, and for those receiving dialysis or transplant therapy.